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Author Topic: Adapting an optical mouse sensor for feedback?
westech
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Post Adapting an optical mouse sensor for feedback?
on: October 11, 2017, 04:39
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Not that it needs it,

But I just replaced my optical mouse with a Logitech 325c (a great little mouse). I got it for $9. I'm sure most of us have an old mouse we don't use.

If you follow Josef Prusa, he uses an optical "mouse" sensor in the new MK3 printer to sense the filament.

Since this little pieces is so small and cheap, I was wondering if there would be any benefit, of reading the X,Y movement and position like a PID.

You tell it to move 20mm right and the sensor provides feedback if it actually moved that far?

I'm not a coder, so I don't have a clue how this could be implemented, but I thought I'd through it out there a something for the future.

Max

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sandy
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sandy
Post Re: Adapting an optical mouse sensor for feedback?
on: October 16, 2017, 22:24
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I've thought about this often - seems like a brilliant idea doesn't it? I've never tried it though. There seems to be lots of skepticism about using optical sensors for other motion-control products (CNC machines like 3d printers).

I know mice are good for relative movements, but I don't know that I could trust it for absolute positioning over metres, and over hours.

Worth a re-investigation though...

sn

westech
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Post Re: Adapting an optical mouse sensor for feedback?
on: October 17, 2017, 17:55
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Perhaps not to map the full print job, but what if you send the pen from a to b. And that is 7mm down by 3mm right, and the optical sensor says you traveled 6.9mm down by 3.1mm right.

You could adjust the position. Or certainly you could calibrate a plotter. Have it draw a square or circle a specific dimension 100mm x 100mm. and the result of the optical sensor can calculate the offset needed.

Again, if you can wire in a $4 sensor.

Just a thought.

Max

sandy
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sandy
Post Re: Adapting an optical mouse sensor for feedback?
on: October 22, 2017, 00:08
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There isn't really a difference between local and overall accuracy - except the scale of it. The point is the sensor will tell you that you travelled 6.9mm one movement, then 6.8mm the next time you send the command, then 7.2mm the next time. It's non-linear, and always "ish", and the error will compound over time like with any dead-reckoning system. There's twist and jitter.

Here is a study about using multiple mouse sensors to increase the reliability of dead-reckoning in mobile robot platforms.

I would _love_ to wire in some $4 sensors!

sn

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